1. Field of the Invention
This invention generally relates to document handling after a document has been printed. More specifically, this invention relates to an apparatus for receiving printed documents and controlling the extent of free flight of the documents when fed into the apparatus.
2. Description of the Prior Art
There are numerous envelope and sheet hopper patents and publications in the prior art. In some cases, these envelope and sheet hoppers employ elevator platforms which are power driven by means of a motor, gears, and a leadscrew. In other cases, belt drive systems are utilized. In the majority of instances, motor drives and controls are employed. There are no known hoppers though, which both employ a gravity system for lowering a platform carrying stack of envelopes or sheets and require an operator to raise the platform to its uppermost position following unloading of the stack.
U.S. Pat. Nos. 2,950,107; 2,992,820; 3,008,709; 3,062,533; 3,062,534; 3,123,355; 3,227,443; 3,301,551; 3,402,928; 3,458,187; 3,664,663; 3,687,448; 3,759,509; 3,768,806; 3,806,112; 3,819,174; and 3,883,132; IBM Technical Disclosure Bulletin, October 1965, Vol. 8, No. 5, page 791 entitled "Document Platform Raising Device"; and British patent 1,122,627 entitled "Sheet Feed Mechanism", filed Sept. 2, 1965, and issued Aug. 7, 1968 were considered in conjunction with this invention. Although none of the above art is considered particularly pertinent to the claims attached hereto, a representative portion of the above mentioned art will be discussed. The above-mentioned IBM TDB describes a document platform raising device which is actuated by a switch mechanism having an arm resting against the upper most document of a stack. When the switch is tripped, a logic mechanism is moved from its latching position, allowing a continously rotating cam to apply drive power to a chain elevator mechanism. The above-mentioned British patent relates to a sheet stack advancer for a sheet feed mechanism in which the stack of sheets is periodically advanced to a predetermined height so that the top most sheet of the stack is in proper operable relation to an associated sheet separation and advancing mechanism. An electric motor is operatively connected to the platform to drive the platform in one direction to raise it and in another direction to lower it. U.S. Pat. No. 2,950,107 relates to an elevator pallet for a continuous top sheet feed apparatus. The pallet is supported by cables which are in turn connected to a winding drum. The drum is rotated by a reversable electric motor supported on a frame. U.S. Pat. No. 3,301,551 relates to a paper stack advancing mechanism for use in a reproduction machine. An automatic control device maintains the level of the paper stack in the paper feed mechanism at a predetermined height so that the top most sheet may be readily forwarded by a sheet feed apparatus. U.S. Pat. No. 3,768,806 relates to apparatus for regulating the position of a platform upon which sheets of material are stacked in order that the top most sheet may be fed and the stack may be replenished.
U.S. Pat. No. 3,883,132 is directed toward an automatic feeding control for a duplicating machine. In this patent a latch lever is employed which rests on the top sheet of a stack of sheets which are to be fed. As feeding progresses and the stack of sheets decreases in height, a latch lever is operable to terminate feeding. Following loading or replenishing of the supply of paper and movement of the platform upward such that the latch lever is again raised to the desired level, feeding automatically commences.
From the above, there is no disclosure or teaching of a hopper employing gravity for lowering a document platform and requiring manual raising for resetting for continued acceptance of documents. With this invention, the necessity for drive motors, elaborate controls, and expensive mechanism is overcome.